One of the prior art multi-polar connectors 61 for interconnecting printed circuit boards is shown in FIGS. 22 to 24. It comprises a depressed connector housing 62 of a rectangular parallelepiped shape. A number of vertical holes 67 pierced in and extending between the top 65 and bottom 66 of the connector housing are for insertion of terminal pins (not shown). A front wall 63 and a rear wall 64 respectively have horizontal slots 68 pierced therein. Each of those slots 68 arranged to form an upper row and a lower row does extend to intersect the corresponding one of vertical holes 67 at a right angle. Upper contacts 71 are inserted in the upper row of slots 68, with lower contacts 72 being for insertion into the lower row of these slots. Each contact 71 and 72 has a pin receiving portion (not shown) that engages with the pin inserted in the slot. Each contact further has a body portion extending rearwards from the pin receiving portion. A rear end region of the body portion is bent down and then rearwards to form a lead portion 73. One of the printed boards 75 has a circuit pattern 76 that is to be soldered to such lead portions 73 of the contacts. The other printed circuit boards not shown but mating with the one printed board does have terminal pins that are surface mounted to fit in the vertical holes 67. Said pins from the mating printed board thus engage with pin receiving portions and establish electric connection to the upper or lower contacts 71 and 72.
In the connector 61 described above, its upper and lower contacts 71 and 72 correspond to the respective vertical holes 67 and electrically engage with the circuit pattern 76 of printed board 75. Thus, a number of signal connections as well as and a number of grounding connections are provided for this circuit board. In FIG. 23, such signal connections are indicated by the symbol ‘S’, with grounding connections being indicated by ‘G’. Each signal connection ‘S’ is surrounded by several grounding connections ‘G’ so that noise is eliminated from or diminished in signal transmission.
In a case of using such a connector 61 to construct the electric circuit for a hard disc drive or the like device, it has to match any elevated speeds of signal transmission. In detail, for the purpose of eliminating noise, arrangement of the signal connections ‘S’ and grounding connections ‘G’ will often be changed in the circuit pattern on the printed board 75.
The contacts 71 and 72 in the prior art connector 61 are all discrete members operating independently of each other. Therefore, another printed board 77 of a different circuit pattern 78 should be employed as shown in FIGS. 25 to 27. Such an alternative circuit board is indispensable to change the relative positional relationship between those signal and grounding connections ‘S’ and ‘G’.